Fostok Sabreen, El-Sibai Mirvat, Bazzoun Dana, Lelièvre Sophie, Talhouk Rabih
Department of Biology, Faculty of Arts and Sciences, American University of Beirut (AUB), Beirut 11-0236, Lebanon.
Department of Natural Sciences, School of Arts and Sciences, Lebanese American University (LAU), Beirut 11-0236, Lebanon.
Cancers (Basel). 2019 Mar 8;11(3):339. doi: 10.3390/cancers11030339.
(1) Background: The expression of connexin 43 (Cx43) is disrupted in breast cancer, and re-expression of this protein in human breast cancer cell lines leads to decreased proliferation and invasiveness, suggesting a tumor suppressive role. This study aims to investigate the role of Cx43 in proliferation and invasion starting from non-neoplastic breast epithelium. (2) Methods: Nontumorigenic human mammary epithelial HMT-3522 S1 cells and Cx43 shRNA-transfected counterparts were cultured under 2-dimensional (2-D) and 3-D conditions. (3) Results: Silencing Cx43 induced mislocalization of β-catenin and Scrib from apicolateral membrane domains in glandular structures or acini formed in 3-D culture, suggesting the loss of apical polarity. Cell cycle entry and proliferation were enhanced, concomitantly with c-Myc and cyclin D1 upregulation, while no detectable activation of Wnt/β-catenin signaling was observed. Motility and invasion were also triggered and were associated with altered acinar morphology and activation of ERK1/2 and Rho GTPase signaling, which acts downstream of the noncanonical Wnt pathway. The invasion of Cx43-shRNA S1 cells was observed only under permissive stiffness of the extracellular matrix (ECM). (4) Conclusion: Our results suggest that Cx43 controls proliferation and invasion in the normal mammary epithelium in part by regulating noncanonical Wnt signaling.
（1）背景：连接蛋白43（Cx43）的表达在乳腺癌中被破坏，在人乳腺癌细胞系中重新表达这种蛋白会导致增殖和侵袭能力下降，提示其具有肿瘤抑制作用。本研究旨在从非肿瘤性乳腺上皮开始，研究Cx43在增殖和侵袭中的作用。（2）方法：将非致瘤性人乳腺上皮HMT - 3522 S1细胞和转染了Cx43短发夹RNA的对应细胞在二维（2 - D）和三维（3 - D）条件下培养。（3）结果：沉默Cx43会导致β - 连环蛋白和Scrib在三维培养形成的腺泡结构或腺管的顶侧膜结构域中定位错误，提示顶端极性丧失。细胞周期进入和增殖增强，同时c - Myc和细胞周期蛋白D1上调，而未观察到Wnt/β - 连环蛋白信号的可检测激活。迁移和侵袭也被触发，且与腺泡形态改变以及ERK1/2和Rho GTPase信号激活有关，后者在非经典Wnt途径下游起作用。仅在细胞外基质（ECM）允许的硬度条件下观察到Cx43 - shRNA S1细胞的侵袭。（4）结论：我们的结果表明，Cx43部分通过调节非经典Wnt信号来控制正常乳腺上皮中的增殖和侵袭。
